This invention relates to an automatic press, this press being used, in particular for the manufacture of compact parts by sintering a powder. It is applied also, to the formation of any object for which the dimensions obtained by the pressing operations must have great precision. More precisely, the automatic press of the invention includes two plates of which at least one is movable in translation along an axis by the action of a jack the position of which is controlled in relation to a predetermined set position. The pressure exerted by the piston of the jack on the plate is, itself, also controlled by control means.
No press is known at present for which it is possible to control simultaneously and with precision, the position of the movable plate or plates comprising it, as well as the force exerted by jacks on the object.
Presses are known in which it is only possible to control the forces of pressure exerted on the plates, but is not possible to control simultaneously the exact positions of the plates. Presses are also known (with screw, for example), in which it is only possible to control the positions of the plates, but is not possible to control simultaneously the pressure forces exerted on these plates.
The purpose of the invention is to remedy these defects and, in particular, to obtain an automatic press in which there can be controlled simultaneously the positions of movable plates as well as the forces exerted on these plates by the jacks which command their movements.
The invention has for its subject an automatic press, which includes a first plate, movable in translation, parallel to a vertical axis, and a hydraulic jack of which the piston, which is secured to the first plate, commands the translation movement of the latter to bring it into a predetermined position, referenced in relation to a reference position which in turn is fixed in relation to the frame, along the vertical axis, this jack being supported by a frame. The press also includes a second plate which supports an object to be pressed, this second plate being situated facing the first plate. The jack includes means for controlling the position of the plate to the predetermined set position, and opto-electronic means for referencing the momentary positions of the first plate in the course of its movement, these opto-electronic means being connected to the control means of the jack commanding the movement of the plate.
According to another characteristic of the present invention, the second plate is also a plate movable in translation parallel to the vertical axis. The second plate is integral with or secured to the piston of another hydraulic jack, the piston of this other jack commanding the movement of this second plate to bring it into another predetermined set position, referenced in relation to a reference position, fixed in relation to the frame. The other jack is supported by the frame, and includes other means for controlling the position of the second plate with this other predetermined position. Other opto-electronic means for referencing the momentary positions of the second plate in the course of its movement are connected to other control means of this other jack which commands the movement of the second plate.
According to another characteristic of the present invention, the first and the second plates include, respectively, force detectors supplying, respectively, signals indicating the forces exerted on the first and second plates, during the pressing or during the distancing of the plates, these detectors being connected to means for controlling these forces. The jacks are connected to these control means to stop the movement of the plate for which the force indicated by the detector is greater than a predetermined limit force.
According to another characteristic of the present invention, the opto-electronic control means are HEIDENHAIN coders.